Agricultural implements such as planters and grain drills typically include mechanisms which meter or dispense individual seeds to the ground. As the implement is drawn across a field, seeds are preferably deposited into furrows in the ground. As will be appreciated by those skilled in the art, the seeds which are planted vary in size, weight and shape depending upon the particular planting.
Various types of seed metering mechanisms are known in the art. Some seed metering mechanisms are a mechanical type wherein individual seeds are picked from a seed mass and discharged to the ground for deposit within the furrows by mechanical devices. Other seed metering mechanisms utilize an apertured rotating disk that operates under the influence of air pressure differentials. Other metering mechanisms rely on a rotating drum that picks up seed from a seed mass and delivers the seeds through elongated air conduits for deposit within the furrows.
Regardless of the type of seed metering mechanism used, it is desirable to deposit a given quantity of seeds within a furrow over a predetennined distance. Also, it is important that the seeds be delivered to the ground in such a way that adjacent seeds within a furrow are generally equidistantly spaced relative to each other along the length of the furrow. To properly deposit the seeds within the furrow requires not only that the seeds be periodically dispensed from the metering apparatus in generally uniform relation relative to each other, but also that the seeds are directed toward and deposited into the furrow with minimal disturbance being imparted to the seeds as they pass from the seed metering mechanism to the ground.
In one form, the seed metering mechanism is typically arranged in combination with a seed hopper that is carried by the agricultural implement and moves along therewith at some nominal speed. It is known to mount a series of seed hoppers in side-by-side relation with each other with each seed hopper having its own seed metering mechanism for controlling the discharge of seeds to the ground as the implement is pulled there across.
Proper deposit of the seed into the furrow promotes planting, growing, and subsequent harvesting procedures. If the individual seeds are released from a housing of the seed meter for essentially vertical straight down movement into the furrow below under the effects of gravity, the ability to positively control the seed deposit is lost. Because the seed meter mechanism is not positioned immediately adjacent to the ground surface, the seeds discharged would normally establish a vertical velocity before they strike the ground.
Moreover, and because of the movement of the seed metering mechanism with the implement, the individual seeds exhausted from the housing of the seed metering mechanism likewise have a horizontal component of movement. The furrow openings wherein the seeds are to be deposited are created in soil and cannot be exact. Thus, the vertical and horizontal velocity components of the seeds discharged from the seed metering mechanism frequently cause the seeds to bounce upon engagement with the soil and away from the intended landing area, resulting in inaccurate and nonuniform distribution of the seeds within the furrow.
To better control the individual seeds as they are discharged from the housing of the seed metering mechanism, it is known to use a seed tube depending from a seed discharge area of the seed metering mechanism and extending toward the ground. These known seed tubes have an upper portion with a relatively straight configuration in the seed discharge area of the seed metering mechanism to provide a relatively smooth reception of the seeds into the tube. Such tubes are also known to include a curvature along a lower portion of the tube. The curved configuration at the lower portion of the tube serves a dual purpose. First, the configuration of the tube is curved a sufficient amount relative to the upper portion of the tube to control the vertical velocity component of the seed as it gravitationally moves toward a discharge end of the tube. Second, the curved configuration of the lower portion of the seed tube is such that it minimizes or eliminates the horizonal velocity component of the seeds as they are discharged to the ground. It is known to configure the lower portion of the tube with a vertically curved configuration in a direction opposite to the normal direction of the implement across a field. The seeds are thereby caused to exit from the seed tube with the horizontal velocity component of the seeds being generally equal to and opposite the horizontal velocity of the implement over the ground.
While such configured or curved tubes have proven effective in controlling the vertical velocity component of the seeds as they move through the tube while minimizing or eliminating the horizontal velocity component of the seeds moving through the tubes, such seed tubes have been known to introduce problems of their own which detract from the advantages obtained through their use in combination with seed metering mechanisms. A significant problem involving such seed tube relates to the inherent tendency for the seeds to rattle or bounce as they move through the tube. The vibrations inherent with the seed tube as it moves across the field exacerbates the seed deflection and delivery problems. Moreover, and because the seeds exhausted from the housing of the seed metering mechanism are of different sizes and shapes, each seed will have a different surface friction contact which tends to slow, delay and alter seed travel as it moves between upper and lower ends of the seed tube. As a result of such bouncing and frictional engagement with the tubes the seeds tend to exit the seed tube at different times and in unpredictable manners As will be appreciated, the inability to maintain substantially equidistance spacing between the seeds as they travel through the tube while likewise losing the ability to maintain substantially constant or uniform discharge of the seeds from the tube, results in nonuniform seed spacings within the furrow.
Thus, there is a need and a desire for a seed tube which is adapted to receive seeds from a seed metering mechanism and which is capable of controlling gravitational movement of the seeds by minimizing surface friction and seed bouncing as the seeds move along a predetermined pathway thereby enhancing controlled delivery of the seeds to the ground.